Free-flowing granular detergent compositions containing nta and soap

ABSTRACT

A GRANULAR DETERGENT COMPOSITION WITH IMPROVED FREEFLOWING PROPERTIES IS OBTAINED BY MAKN A SLURRY OF NONIONIC SYNTHETIC DETERGENT, ANIONIC SYNTHETIC DETERGENT AND BUILDING MIXTURE OF A WATER SOLUBLE ALKALI SALT OF NITRILOTRIACETIC ACID AND AN ALKALINE TRIPOLYPHOSPHATE, HEAT-DRYING THE SLURRY AND THEN ADDING SOAP TO THE HEAT-DRIED COMPOSITION.

April 27,1971 5. e. PETERSSON 3,575,743

* FREE-FLOWING GRANUL KR DETERGENT COMPOSITIONS CONTAINING NTA AND SOAP 2 Sheets-Sheet 1 Filed April' 1. 1969 f} m w 7 v 7a &&| w w v,

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INVENTOR:

SIGVARD GUNNAR PE BY 1s ATTORNEY April 27,1971 s. s. PETERSSON 3,576,748

' N FREE-FLOWING GRANULAR DETERGENT COMPOSITIONS CONTAINING NTA AND SOAP Filed Aprilpl. 1969 d 2 Sheets-Sheet 2 INVENTOR SIGVARD GUN NAR PETERSSON BY 1,; 1g, 97.

IS ATTORN Y United States Patent 3,576,748 FREE-FLOWING GRANULAR DETERGENT COM- POSITIONS CONTAINING NTA AND SOA P Sigvard Gunnar Petersson, Nykoping, Sweden, assignor to Lever Brothers Company, New York, N.Y. Filed Apr. 1, 1969, Ser. No. 812,125 Claims priority, application Luxembourg, Apr. 3, 1968,

,829 Int. Cl. C11d 9/14, 9/30, 11/00 U.S. Cl. 252-110 2 Claims ABSTRACT or THEDISCLOSURE The present invention relates to a process for preparing a detergent composition. More particularly, the present invention relates to a process for preparing a detergent composition which comprises an active detergent mixture of a nonionic synthetic detergent, an anionic synthetic detergent and an alkali metal soap, and a builder mixture of an alkali polyphosphate and a water-soluble alkaline salt of nitrilotriacetic acid.

Nitrilotriacetic acid, in particular the water-soluble alkali salts thereof, hereafter referred to as NTA, is a well-known sequestering agent. It has been proposed to use NTA in combination with an alkalipolyphosphate, in particular sodiumtriphosphate (hereinafter referred to as STP) to provide a builder mixture for detergent compositions.

According to the prior art, a spray-dried detergent composition containing this NTA/STP builder mixture could be prepared by preparing an aqueous slurry containing the various active detergent ingredients and the NTA/STP mixture together and spray-drying said slurry in any conventional way.

This method, however, does not produce satisfactory results if the active detergent mixture comprises a mixture of a nonionic synthetic detergent, an anionic synthetic detergent and an alkali metal soap, a so-called controlled sudsing detergent composition. If a slurry containing this active detergent mixture and an NTA/STP mixture is spray-dried in a conventional manner, the spray-dried powder obtained is soft and very hygroscopic, and has poor free-flowing properties. It feels wet and sticky on leaving the spray-tower.

In addition the spray-drying operation is diflicult because burning often occurs in the powder at the hot-air intake in the spray-tower.

It has now been found that these disadvantages can be significantly reduced if the soap content of the aqueous slurry is decreased.

The present invention therefore provides a process for the preparation of a granular free-flowing detergent composition containing an active detergent mixture consisting of a nonionic synthetic detergent, an anionic synthetic detergent and an alkali metal soap, and a mixture of NTA and STP in which an aqueous slurry containing the NTA, the STP and the nonionic synthetic detergent, the anionic synthetic detergent, and less than the total amount of the soap required in the final composition, is heat-dried, and the remaining part of the required amount of the soap is then added to the heat-dried granular detergent composition. The granular detergent composition thus obtained has satisfactory free-flowing properties, and the 3,576,748 Patented Apr. 27, 1971 "ice hygroscopicity of the product is considerably reduced. Moreover, the aqueous slurry is more easily heat-dried.

As stated above, the aqueous slurry should contain less than the total amount of soap required in the final product. Reduction of this amount results in better products, and the best products are obtained if the slurry does not contain soap at all. In this case all of the soap is added afterwards to the heat-dried product.

The soap can be added in any convenient form for instance as shaped solids. By shaped solids is to be understood any suitable solid form obtained by a suitable shaping process. Suitable shaped solid forms are noodles, flakes, ribbons, threads, granules, pellets, small spheres, etc.

The soap can contain other ingredients desired in a detergent composition, such as perfumes, germicides, colouring material, fluorescers, enzymes, tarnish inhibitors, corrosion inhibitors, etc.

The aqueous slurry can be prepared in any conventional manner by mixing the constituents of the detergent composition with sufficient water in a crutcher. The amount of water (including that present in the various ingredients added to the slurry) should be sufiicient to ensure a thinly viscous, readily pumpable and homogeneous slurry which does not gellify or solidify at higher shear rates, e.g. when the slurry is pumped through a high-pressure pump or a colloid mill. In general, the amount of water should be from 45-55% by weight of the final slurry. The final slurry temperature should in general not be higher than 85 C., and preferably not higher than about 70 C. During the mixing operation the temperature of the slurry may increase when particular ingredients are added, such as e.g. sodium carbonate, and in general the initial temperature of the water should lie therefore between about 50 and 60 C.

The heat-drying can be carried out in any conventional manner in a drying apparatus. The slurry is preferably spray-dried, e.g. in a spray-drying tower. The detergent composition of the invention may contain a mixture of NTA and STP in an amount of 20-50% by weight of the final composition. In general, the mixture contains NTA and STP in a molar ratio of 4:1 to 1:4. A preferred molar ratio is 1:1.

The detergent composition of the invention contains an active detergent mixture containing a nonionic synthetic detergent, an anionic synthetic detergent and an alkali metal soap.

Preferred nonionic synthetic detergents for use in the present process are alkylene oxide containing nonionics. These are condensation products of alkylene oxide with an organic hydrophobic compound. Examples thereof are condensation products of ethylene oxide with alcohols, monoand di-alkylphenols, fatty acid amides, polyalkylene glycols and mixed alkylene oxide adducts. In general, the composition contains from 110% by weight of the final composition of the nonionic synthetic detergent. For medium-sudsing purposes l 6% if preferred, and for lowsudsing 2-l0% if preferred.

The anionic synthetic detergents which may be used in the present process are well-known in the detergent art. They can be broadly described as the alkaline salts of the reaction product of a sulphating or suphonating agent with an organic sulphatable or sulphonatable compound. Examples thereof are the alkyl sulphates, alkylether sulphates, alkyl sulphonates, alkylaryl sulphonates, alkylarylether sulphates, acyltaurides, acylisethionates, sulphofatty acids, olefin sulphonates, etc.

In general, the composition contains from 2-20% by weight of the final composition of the anionic synthetic detergent. For medium-sudsing generally from 8-15% is desired, for low-sudsing generally from 29% being suitable.

The soaps which are preferably used in the present process are of the normal type of soaps currently used in the detergent art, such as the alkali metal soaps of saturated fatty acids having from 10'-24 carbon atoms in the alkyl chain, e.g. fatty acids derived from palm oil, groundnut oil, hardened tallow, hardened fish oil, etc. Also alkali metal soaps of synthetic fatty acid may be used. In general, the composition contains from 1-10% by Weight of the final composition of soap. For mediumsudsing an amount of 1-5% is preferred, for low-sudsing 5-10% of soap being desirable.

The composition may further contain normal detergent additives, such as hydrotropes, lather modifiers, soilsuspending agents, fabric-damage inhibitors, corrosion inhibitors, alkali salts such as sodium carbonates, silicates, sulphates, sequestering agents, and hydrophobes such as paratfins. For heavy-duty purposes, a bleaching agent such as sodium perborate may be added in an amount of up to 35%. Enzymes may also be added.

The invention will now be further illustrated by the following examples:

EXAMPLE 1 Aqueous slurries were prepared by mixing at about 50 C. the following constituents:

Kg. Sodium alkylaryl sulphonate (40% AD.) 850 Nonylphenol E0 82 Sodium triphosphate (phase II) 200 Trisodium nitrilotriacetate (92, 93%) 322.6

Waterglass (Na O. 1.8 SiO (35%) 440 Sodium carboxymethylcellulose (65 14.5 Soda ash 408 Paraffin 28 Fluorescers 8.6 Sodium toluene sulphonate (93%) 6 EDTA (80%) 2.5 Sodium thiosulphate 0.3 Water 850 in a crutcher with different amounts of sodium soap of tallow class fats (63% f.a.), viz. 170, 73.4, 54.0, 32.4 and 0 kg. of soap. The final slurry temperature was about 70 C. Spray-drying these slurries yielded powders with 7.5, 3.4, 2.5, 1.5 and 0% of soap.

The following properties of these spray-dried powders were determined after the powders had matured for 3 days:

(I) I-Iygroscopicity: moisture uptake (percent increase in weight) at 80% RH. at room temperature (about 22 C.) in an open beaker containing 50 cc. of the powder during 7 days of storage.

(II) Compressibility: percent decrease in volume of a certain volume of powder (390 cc.) under a certain pressure on the powder (1130 g./cm. after 1 minute.

(III) Flowing time: time in seconds for 4 litres of powder to pour out from a cone having an orifice of 28 mm. diameter.

Also the bulk densities (IV) of the powders in g./l. were determined. The results are shown in FIG. 1. From this figure it is clear that a reduction of the soap content in the powder provides a lower hygroscopicity, a shorter flowing time, a lower compressibility and a higher bulk density. The products become less hygroscopic, more free-flowing, less sticky and have a. higher bulk density.

EXAMPLE 2 Aqueous slurries were prepared at about 50 C. by mixing the constituents of Example 1 with such amounts of soap (hardened tallow 63% f.a.) that on spray-drying powders were obtained with A 8.6, B 7.56, C, 3.38, D 1.6 and E 0% soap. To products B, C, D and E 22% of sodium perborate was added after spray-drying, and to products C, D and E also soap noodles (hardened tallow; 85% soap) in an amount of 4, 5.5 and 6.9% respectively. These products were stored in an open beaker at RH. at room temperature (about 22 C.) for 4 weeks, and the increase in weight (in percent) was determined every week. The results are shown in FIG. 2. From this figure it is clear that reducing the amount of soap in the spray-dried powder provides significantly less hygroscopic powders.

The compositions of the invention are satisfactory controlled sudsers, and are suitable for use in drum-type washing machines.

What is claimed is:

1. A process for the preparation of a granular detergent composition with improved free-flowing properties wherein said composition consists essentially of:

(a) 1 to 10% by weight of a nonionic synthetic detergent;

(b) 2 to 20% by weight of an anionic synthetic detergent;

(c) 20 to 50% by weight of a mixture of sodium tripolyphosphate and an alkali metal salt of nitrilotriacetic acid wherein said tripolyphosphate and said nitrilotriacetic acid salt are present in a range of a ratio of from 4:1 to 1:4 on a molar basis; and

(d) 1 to 10% by weight of a sodium soap of saturated fatty acids having 10 to 24 carbon atoms in the alkyl chain;

said process comprising heat drying an aqueous slurry containing all of ingredients (a), (b) and (c) and not more than half of ingredient (d) and, thereafter adding to said heat-dried product the remainder of the sodium soap as shaped solids in the form of noodles, flakes, ribbons, threads, granules, pellets or small spheres.

2. A process according to claim 1, characterised in that all of the soap is added after the slurry is heat-dried.

U.S. Cl. X.R. 

